The consumption of meat is one of the largest contributors to emissions of greenhouse gases worldwide. This is partly indirect because 80% of for-agriculture deforestation is for the growing of fodder for farmed animals (see the sources in this post), partly more direct due to the high amounts of energy required for production and logistics of meat, partly due to rumination, partly due to other effects. For supporting research, see the answer to this and this question on Skeptics SE.
Despite all the evidence, policy discussions on reducing carbon footprints seem to be hardly about meat, if at all. Discussions seem to focus on industry, transportation, and electricity production, despite the fact that a reduction in meat consumption would have other benefits, besides a reduced carbon footprint. I speculate the reason it hasn't been discussed is because any suggestion on a meat tax would be hugely impopular with electorate.
Speculation aside, does a meat tax exist anywhere in the world? If yes, where? If no, has it been close to being introduced anywhere?